<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒子模型</title>

    <style>
        body {
            border: blue solid 4px;
        }
        div {
            width: 200px;
            height: 200px;
            background-color: deeppink;

            /*内边距*/
            padding: 20px;
            /*边框：边框粗细和实线虚线必填*/
            border: 4px solid;
            /*外边框*/
            margin: 20px;
        }
    </style>
</head>
<body>
<div>
    我是一个div标签
</div>
</body>
</html>